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caustic potash solution. After filtering, the alumina is precipitated as phosphate of alumina either by acetate of ammonia or by addition of ammonia to neutrality. I will present here a fourth method in which the lime is thrown out as oxalate of lime in an oxalic acid solution. After filtering from the oxalate of lime the excess of oxalic acid present is removed by destroying with sulphuric acid. The iron and alumina are then precipitated as phosphates. This new method has been carefully tested by the use of solutions containing known amounts of iron, of alumina, and lime. Chemically pure iron wire, sheet aluminum, and carbonate of lime were employed to make these solutions. Analyzing such solutions I obtained Taken. Gram.
Found. Gram.
Calcium oxide. . . . . . . . . . . . . . . . . 0 , 0 0 8
0,008
Calcium oxide.. . . . . . . . . . . . . . . . 0.200
0.0083 0.0094 0.2005
The new method was also tested by analyzing a number of phosphate rocks in comparison with the caustic potash method with results as follows: Potash method. Per cent. Alumina. ..................... 4.20 " ....................... 2.70 .... . 1.40 t' ...................... 1.75 " ...................... 1.49 " ...................... 1.37 " ...................... 3.35 ......... 1.79 ... 1 .50 ... 1,85
.
Oxalate method. Per cent. 4.24 2.63 1 .32 1.67 1.59 1.25 3.35 1.75 1.49 1.95
The new method is carried out in detail as follows: Boil j grams of the rock phosphate for one hour in 50 cc. HC1 ( I : I ) ; filter into a 2 j o cc. flask, add a few cubic centimeters of peroxide of hydrogen solution, boil for a few minutes to oxidize iron and expel oxygen, cool, fill to mark and mix. Take 25 cc. (3 gram), heat to boiling, add ammonia to alkalinity, then HC1 till just clear, then I gram of oxalate of ammonium in crystals, boil gently for a short time, let settle and filter from precipitated oxalate of lime into a 500 cc. Kjeldahl flask, add 5 cc. concentrated sulphuric acid, evaporate to white fumes to destroy excess of oxalic acid. (This boiling down and destruction of oxalic acid can be done in twenty minutes.) Cool, add j o cc. water, 5 cc. strong HC1, and boil gently a few moments to dissolve any dehydrated sulphate of iron, boiling until solution is clear. Rinse into beaker, make up to about I jo cc. and precipitate the iron
and alumina as phosphates either by adding ammonia to neutrality using methyl orange as an indicator, or by making the solution just alkaline with ammonia, just clearing with hydrochloric acid and then adding 2 j cc. of acetate of ammonia solution (sp. gr. 1.04). Filter and wash the precipitated phosphates with a boiling hot nitrate of ammonia solution ( 2 4 per cent.). Ignite and weigh, deduct the iron phosphate present and multiply the remainder by 0.418 to obtain the alumina. The iron oxide is determined by taking jo cc. ( I gram) of the rock phosphate solution and titrating by either bichromate of potash solution or permanganate of potash solution. LABORATORY OF STILLWELL GLADDING, NEWYORK.
THE ANALYSIS OF COMMERCIAL ACETATE OF LIME. By THOMAS S. GLADDING, A.M. Received January 29, 1909.
The exporting of commercial acetate of lime assumed noticeable proportions about the year 1890. In the early part of 1902 the exporters abandoned the so-called " English Commercial Test" and called for the estimation of acetic acid by distillation. For some time we used a process where the acetic acid was distilled with an excess of phosphoric acid, the distillation being assisted by a current of steam constantly blown through the body of the distilling liquor. This process was more complex than a simple distillation and great care had to be exercised against a dangerous tendency to carry over phosphoric acid. The cons'tant tendency toward high results led to our abandoning this method, in favor of a new process, devised by myself in 1902. I n this new process the use of a current of steam was abandoned for what I may call a "Continuous Constant-Volume Distillation." The method by which this is accomplished is the original feature of this process and is illustrated by the accompanying figure. The distillation flask A is closed with a double perforated rubber stopper. The tube E connects with the condenser C. The tube D connects with a reservoir, containing water free from carbonic acid. A screw pinch-cock a t H regulates the flow of water, allowing it to enter drop by drop and maintaining the contents of the flask a t a constant volume. I n this new process two grams of acetate of lime are introduced into a Kjeldahl flask A (about
9
GLADDING ON COilIMERCIAL A C E T A T E OF LIiWE.
2j 1
E , is condensed in condenser C and received in flask B which contains, 30 cc. standard alkali solution.
Phenolphthalein is used as an indicator. A blank experiment is run and the small amount of acidity obtained in this blank is deducted from each subsequent analysis. In the Zeitschrift f u r analytische Chemie, 1908, p. 597, there has been published by W. Fresenius and I,. Griinhut, a paper comparing the different methods for the estimation of acetic acid in crude acetate of lime, by distillation with phosphoric acid. The authors make a study of four methods, first that of R. Fresenius, second that of the Color Works of F. Bayer & Co., Elberfeld, third that of K. R. Haberland, and fourth the continuous method devised by myself. They condemn all the methods excepting the second, asserting that they give results too high. They attribute the excessive amount of volatile acid obtained, to a decomposition of the organic constituents of the acetate of lime and the formation of butyric acid. This decomposition they claim is due to too great a concentration of the distillant.’ This present paper will interest itself only in their criticism of my method. They speak of it in the following words: We must reach the conclusion that the errors we find in the R. Presenius method are not excluded.” “ We cannot recommend the working of this method.” “The analyses show a tendency to go upward.” In answering these criticisms I call special attention to one important matter. The two novel features of my method are first the constant volume of the distillant, about 5 0 cc. when using 2 grams of acetate; and second the abandonment of a current of steam and the substitution therefor of the addition of water drop by drop. They state that in testing this method they maintained the volume at about j o cc. but in one case they used 5 grams to 50 cc. and in another z grams to 5 0 cc. It is evident that when they used j grams to jo cc. they were not using my method. Again, and far more important, they say that in both cases they employed a “current of steam,” instead of adding water slowly to the distillant. It is evident therefore, that in none of their work did they really use my method and that their results have no value whatever as a criticism of the accuracy of my method. The authors speak of testing the method by a “series” of tests. This “series” consists of four
At the end of one and one-half hours the contents of the flask B are titrated. The distillation is continued until the distillate comes over neutral.
1 A newly coined word, to express the contents of the distilling flask. I t is derived from the present participle distillans (the thing distilling) as distillate is derived from the past perfect participle distillatus (the thing distilled).
300 cc. capacity) with 30 cc. water. Ten cc. phosphoric acid solution, sp. gr. 170, are added, the contents of the flask are boiled gently for about one and one-half hours while the volume is kept at 50 cc. The distillate passes over through tube
I
‘I
B
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analyses of a brown acetate of lime. They also fail to carefully follow the method in its most essential feature, namely, the slow addition of water as a substitute for a current of steam.
To ascertain whether the objections urged by the authors, are of any value as applied to my method, when correctly carried out, I have made a number of analyses, using widely varying degrees of concentration. Thus I have taken 5 grams of acetate of lime, added 2 5 cc. water and 2 5 cc. phosphoric acid solution sp. gr. 1.70, distilled to a volume of 30 cc. and continued the distillation for two hours, till no further volatile acid could be obtained. At the same time, 2 grams acetate plus I O cc. phosphoric acid solution were distilled at a volume of 40 cc. for two hours, also I gram acetate plus 5 cc. phosphoric acid solution was distilled at a constant volume of 50 cc. for two hours, till all volatile acids were ov&. These three experiments were made with a brown acetate of lime, also with a gray acetate of lime. The results were as follows: BROWN ACETATE O F LIME.
One g. Two g. Five g.
+ 5 cc. phos. add sol. at ahstant vol. of 50 cc. gave 67 .SO%. + 10 cc. phos. add sol. at constant vol. of 40 cc. gave 67.75%. + 25 cc. phos. add sol. at constant vol. of 30 cc. gave 67.90%.
One g. T w o g. Five g.
+ 5 cc. phos. acid sol. at constant vol. of 50 cc. gave 83.57%. + 10 cc. phos. add sol. at constant vol. of 40 cc. gave 83.41%. + 25 cc. phos. acid sol. at constant vol. of 30 cc. gave 83.41%.
GRAYACETATE OF LIME.
We notice in these experiments that although the concentration, when using 5 grams, is ten times that when using I gram, nevertheless, no more volatile acid is obtained from the greater degree of concentration. I tested the question still more rigorously and conclusively, by taking the residue of the 5 grams distillant. After expelling all volatile acid, I added 50 cc. water and I gram C. P. acetate of soda. I obtained after exhaustive and continued distillation 100.1 per cent. of acetate of soda. I consider that the above work completely vindicates the method as proposed by myself. I also express the opinion that the high results obtained by Fresenius and Griinhut are due to the use of a current of steam. The experience of Grosvenor is similar to my own. He says:’ “Steam should never be used for distillation.” As has been stated in a n earlier part of this paper, I abandoned the use of a steam current because of its tendency to give results higher than the truth. LABORATORY OF STILLWELL & GLADDING. 1 Jour.
SOC.Chem. I d . , lSO4, p. 535.
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Apr. , 1909
THE RAPID DETERMINATION OF MOISTURE IN COMMERCIAL PRODUCTS OF A VISCOUS OR SEMI-SOLID CONSISTENCY. B y ARTHURLOWENSTEIN. I Received January 16. 1909.
The object of this investigation was to secure a rapid method for the determination of moisture in concentrated solutions of a viscous or semi-solid consistency, such as are frequently encountered in a modern packing-house. Later the method was extended to other products having similar physical characteristics. In the case of some products, such as meat extracts, it is frequently desirable and necessary to secure a rapid determination of the moisture content of the product, in order not to delay the process of manufacture. I n many laboratories in order to facilitate matters, such moisture determinations are conducted by allowing the material to dry in an oven over night. Such prolonged heating of organic nitrogenous material, however, is frequently conducive to chemical decomposition, and the results of the determination are often high. The present methods for the direct determination of moisture in such products as are under discussion, usually consist in drying a definite quantity of the material to a constant weight at a specified temperature (usually that of boiling water, or 105’ C.) either by itself or with the admixture of ignited asbestos, pumice stone, quartz sand, or some similar material. I n this way the moisture is determined in from 5-24 hours, depending upon the nature of the product. When the longer period is required, such as in the case of molasses and fruit jellies, etc., some decomposition is very apt to occur. The method herein employed consists merely in the application of several well-known principles, viz., the addition of a dehydrating agent, of a lower boiling point than water, in which the material to be desiccated is wholly or in part soluble, or a t least miscible. The reagent employed was ethyl alcohol, and for the sake of economy, the ordinary 95 per cent. alcohol (by volume) was used. In the case of materials containing proteins in solution, the alcohol also acts as a coagulant in some cases, and as a precipitant in others, which action facilitates the drying process. The method employed consists in weighing a small quantity of the sample in a metal dish, 2% inches in diameter (the metal 1 Read before the Division of Industrial Chemists and Chemical Engineers of the American ,Chemical Society at Baltimore, Dee. 29, 1908.
